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NEW YORK (Reuters Health) – As a treatment for primary dysmenorrhea, continuous oral contraceptives (OCs) outperform cyclic oral contraceptives, but this advantage is lost after 6 months, according to a report in the June Obstetrics & Gynecology.

“Women who have severe primary dysmenorrhea should probably start OC pills continuously, because they outperform cyclic administration in the short term,” Dr. Romana Dmitrovic from BetaPlus Center for Reproductive Medicine, Zagreb, Croatia told Reuters Health in an email. “From my clinical experience, women with severe dysmenorrhea who take OC pills in a cyclic fashion often do not comply with therapy, because they feel it does not help them fast enough.”

“All other women, those with moderate and mild primary dysmenorrhea, should, in my opinion, take OC pills in a cyclic fashion,” Dr. Dmitrovic said. “They will be good enough for their pain, and if they were put on continuous administration, they will probably not be tolerant to unpleasant side effects.”

Dr. Dmitrovic and colleagues investigated whether continuous OC pills would result in more pain relief than cyclic OC pills would in a randomized controlled trial of 38 primary dysmenorrhea patients. Twenty-nine women completed the study.

Both treatments significantly reduced pain. The continuous regimen provided pain relief superior to the cyclic regimen after 1 and 3 months, but the difference at 6 months was statistically marginal.

Improvements in Moos Menstrual Distress Questionnaire scores were similar for the 2 treatments at all 3 follow-up points.

Compared with women in the cyclic group, women in the continuous group experienced significant increases in weight and body mass index and significant decreases in systolic blood pressure. Both groups had similar decreases in endometrial thickness at 6 months.

Over the 6 months, women on the continuous OC pill regimen had 70% more days of bleeding (58.2 days versus 33.7 days) and 2.6-fold more days of spotting (41.5 days versus 16.0 days) than did women on the cyclic regimen.

“There are still no data on risks associated with long term continuous administration of OC pills, and women should be counseled about this, to make an informed consent,” Dr. Dmitrovic said. “Also, after 3-6 months there are no data on advantages of continuous administration over cyclic administration of pills, and these patients should probably switch to cyclic administration.”

“Further large randomized trials are needed to establish the risk-to-benefit ratio of longer use of extended-cycle OC pill regimens for primary dysmenorrhea,” the researchers note.

“Primary dysmenorrhea is a neglected entity, although the majority of women suffer from it at some point in their lives,” Dr. Dmitrovic said. “I hope this research will remind physicians to ask about dysmenorrhea more often, and if it is confirmed, to treat the condition. In young women, OC pills are absolutely the best solution and should be used more often.”